Methods of controlling clocks in system on chip including function blocks, systems on chips and semiconductor systems including the same

ABSTRACT

A system-on-chip includes a clock controller configured to decrease an operating frequency of at least one function block based on a change in an operating state of the at least one function block from an active state to an idle state. In a method of operating a system-on-chip including at least one function block, an operating frequency of the at least one function block is decreased based on a change in an operating state of the at least one function block from an active state to an idle state. The decreased operating frequency is greater than zero.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. §119(a) to KoreanPatent Application No. 10-2011-0133195 filed on Dec. 12, 2011, thedisclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Field

Example embodiments of inventive concepts relate to systems on chips(SoCs), for example, to methods of controlling operating clock signalsprovided to function blocks in SoCs, SoCs using the method and/orsemiconductor systems including the SoCs.

2. Description of Related Art

A system-on-chip (SoC) is semiconductor integration technology forimplementing relatively complicated components having differentfunctions in a single system. A SoC includes a processor, which controlsthe entire system, and various intellectual properties (IPs) controlledby the processor. Here, an IP is a circuit, a logic or a combinationthereof, which can be integrated into the SoC. Code may be stored in thecircuit or logic.

Systems including a SoC having a plurality of various IPs are usuallydriven by a battery. Consequently, low-power design is relativelyimportant. When a reference clock signal is provided to the SoC by, forexample, a phase locked loop (PLL), each of the IPs operates in responseto an operating clock signal having a different frequency according toits function.

Each IP may be in an active state or an idle mode according to thefunction of the IP. And, different IPs may operate in different modes(e.g., idle or active) concurrently or simultaneously.

When at least one IP is in the active state and at least one IP is inthe idle mode, an operating clock signal for the active state is appliedto the at least one IP in the idle mode as if the IP in the idle mode isin the active state. In this instance, the SoC consumes unnecessarypower. The unnecessary consumption of power may affect the lifespan of abattery, for example, when a frequency of several hundreds of MHz toseveral GHz is used.

SUMMARY

At least one example embodiment provides a method of operating asystem-on-chip including at least one function block. According to atleast this example embodiment, the method includes: decreasing anoperating frequency of the at least one function block based on a changein an operating state of the at least one function block from an activestate to an idle state, the decreased operating frequency being greaterthan zero.

At least one other example embodiment provides a method of operating asystem-on-chip including a function block. According to at least thisexample embodiment, the method includes: detecting a first change in anoperating state of the function block from an active state to aninactive state; decreasing an operating frequency of the function blockin response to the detected first change, the decreased operatingfrequency being greater than zero; detecting a second change in theoperating state of the function block from the inactive state to theactive state; and increasing the operating frequency of the functionblock in response to the detected second change from the inactive stateto the active state.

At least one other example embodiment provides a system-on-chip.According to at least this example embodiment the system-on-chipincludes: a clock controller configured to decrease an operatingfrequency of at least one function block based on a change in anoperating state of the at least one function block from an active stateto an idle state, the decreased operating frequency being greater thanzero.

At least one other example embodiment provides a system-on-chip.According to at least this example embodiment, the system-on-chipincludes: a mode detector circuit configured to detect a change in anoperating state of a function block, the mode detector circuit beingfurther configured to generate a select signal based on the detectedchange in the operating state; and an operating frequency settingcircuit configured to set an operating frequency of the function blockbased on the select signal from the mode detector circuit; wherein theoperating frequency setting circuit is configured to decrease theoperating frequency of the function block if the select signal isindicative of a change from an active operating state to an inactiveoperating state, the decreased operating frequency being greater thanzero, and the operating frequency setting circuit is configured toincrease the operating frequency of the function block if the selectsignal is indicative of a change from the inactive operating state tothe active operating state.

At least one other example embodiment provides a semiconductor system.According to at least this example embodiment, the semiconductor systemincludes: a system-on-chip; a memory configured to store at least one ofprograms and data associated with the semiconductor system; at least oneprocessor configured to at least one of process and execute at least oneof the programs and data stored in the memory; a memory controllerconfigured to interface with external memory; and a display devicecontroller configured to control a display device. The system-on-chipincludes a clock controller configured to decrease an operatingfrequency of at least one function block based on a change in anoperating state of the at least one function block from an active stateto an idle state, the decreased operating frequency being greater thanzero.

At least one other example embodiment provides a semiconductor system.According to at least this example embodiment, the semiconductor systemincludes: a display device; a radio transceiver configured to transmitand receive radio signals via an antenna; and a system-on-chipconfigured to interface with the radio transceiver and the displaydevice. The system-on-chip includes: a clock controller configured todecrease an operating frequency of at least one function block based ona change in an operating state of the at least one function block froman active state to an idle state, the decreased operating frequencybeing greater than zero.

At least one other example embodiment provides a computer system.According to at least this example embodiment, the computer systemincludes: a display device; a memory device; a memory controllerconfigured to control the memory device; an input device; and asystem-on-chip configured to interface with the display device, thememory controller and the input device. The system-on-chip includes aclock controller configured to decrease an operating frequency of atleast one function block based on a change in an operating state of theat least one function block from an active state to an idle state, thedecreased operating frequency being greater than zero.

At least one other example embodiment provides a computer system.According to at least this example embodiment, the computer systemincludes: a display device; an image sensor; a memory device; a memorycontroller configured to control the memory device; and a system-on-chipconfigured to interface with the display device, the image sensor andthe memory controller. The system-on-chip includes: a clock controllerconfigured to decrease an operating frequency of at least one functionblock based on a change in an operating state of the at least onefunction block from an active state to an idle state, the decreasedoperating frequency being greater than zero.

At least one other example embodiment provides a memory system.According to at least this example embodiment, the memory systemincludes: a host; a volatile memory device; a plurality of non-volatilememory devices; a memory controller configured to control the pluralityof non-volatile memory devices; and a system-on-chip configured tointerface with the host, the volatile memory device and the memorycontroller. The system-on-chip includes a clock controller configured todecrease an operating frequency of at least one function block based ona change in an operating state of the at least one function block froman active state to an idle state, the decreased operating frequencybeing greater than zero.

BRIEF DESCRIPTION OF THE DRAWINGS

Inventive concepts will become more apparent by describing in detailsome example embodiments thereof with reference to the attached drawingsin which:

FIG. 1 is a block diagram of a system on chip (SoC) according to anexample embodiment of inventive concepts;

FIG. 2 is a more detailed block diagram of an example embodiment of theSoC illustrated in FIG. 1;

FIG. 3 is a diagram showing an example embodiment of a finite statemachine (FSM) implementation of the mode detector 35 shown in FIG. 2;

FIG. 4 is a more detailed block diagram of an example embodiment of theSoC illustrated in FIG. 1;

FIG. 5 is a diagram showing an example embodiment of a finite statemachine (FSM) implementation of the mode detector 45 illustrated in FIG.4;

FIG. 6 is a timing chart of signals of a SoC according to exampleembodiments of inventive concepts;

FIG. 7 is a timing chart of signals of a SoC according to anotherexample embodiments of inventive concepts;

FIG. 8 is a timing chart of signals of a SoC according to yet anotherexample embodiments of inventive concepts;

FIG. 9 is a block diagram of a SoC according to another exampleembodiment of inventive concepts;

FIG. 10 is a flowchart illustrating a method of controlling a clocksignal according to an example embodiment of inventive concepts;

FIG. 11 is a block diagram illustrating another example embodiment ofthe SoC shown in FIG. 1;

FIG. 12 is a block diagram illustrating yet another example embodimentof the SoC shown in FIG. 1; and

FIG. 13 is a diagram showing an example embodiment of a finite statemachine (FSM) implementation of the mode detector illustrated in FIG.12.

FIG. 14 is a block diagram illustrating other example embodiment of theSoC shown in FIG. 1;

FIG. 15 is a block diagram illustrating yet other example embodiment ofthe SoC shown in FIG. 1;

FIG. 16 is a block diagram of a semiconductor system including a SoCaccording to an example embodiment of inventive concepts;

FIG. 17 is a block diagram of another example embodiment of asemiconductor system including the SoC illustrated in FIG. 1;

FIG. 18 is a block diagram of an example embodiment of a computer systemincluding the SoC illustrated in FIG. 1;

FIG. 19 is a block diagram of another example embodiment of a computersystem including the SoC illustrated in FIG. 1;

FIG. 20 is a block diagram of an example embodiment of a memory systemincluding the SoC illustrated in FIG. 1;

FIG. 21 is a graph showing example current and voltage when an operatingclock signal is applied to a function block without taking into accountthe state of the function block; and

FIG. 22 is a graph showing example current and voltage when an operatingclock signal is applied to a function block when taking into account thestate of the function block.

DETAILED DESCRIPTION

Inventive concepts now will be described more fully hereinafter withreference to the accompanying drawings, in which example embodiments areshown. Inventive concepts may, however, be embodied in many differentforms and should not be construed as limited to the example embodimentsset forth herein. Rather, these example embodiments are provided so thatthis disclosure will be thorough and complete, and will fully convey thescope of inventive concepts to those skilled in the art. In thedrawings, the size and relative sizes of layers and regions may beexaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed itemsand may be abbreviated as “/”.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first signal could be termed asecond signal, and, similarly, a second signal could be termed a firstsignal without departing from the teachings of the disclosure.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Specific details are provided in the following description to provide athorough understanding of example embodiments. However, it will beunderstood by one of ordinary skill in the art that example embodimentsmay be practiced without these specific details. For example, systems(e.g., computer systems, systems-on-chips, etc.) may be shown in blockdiagrams in order not to obscure the example embodiments in unnecessarydetail. In other instances, well-known processes, structures andtechniques may be shown without unnecessary detail in order to avoidobscuring example embodiments.

Also, example embodiments may be described as processes depicted asflowcharts, structure diagrams, block diagrams, etc. Although aflowchart may describe the operations as a sequential process, many ofthe operations may be performed in parallel, concurrently orsimultaneously. In addition, the order of the operations may bere-arranged. A process may be terminated when its operations arecompleted, but may also have additional steps not included in thefigure. A process may correspond to a method, a function, a procedure, asubroutine, a subprogram, etc. When a process corresponds to a function,its termination may correspond to a return of the function to thecalling function or the main function.

At least some example embodiments may be implemented by hardware,software, firmware, middleware, microcode, hardware descriptionlanguages, or any combination thereof When implemented in software,firmware, middleware or microcode, the program code or code segments toperform the necessary tasks may be stored in a machine or computerreadable medium such as a storage medium. A processor(s) may perform thenecessary tasks.

The term “storage medium” may represent one or more devices for storingdata, including read only memory (ROM), random access memory (RAM),magnetic RAM, core memory, magnetic disk storage mediums, opticalstorage mediums, flash memory devices and/or other machine readablemediums for storing information. The term “computer-readable medium” mayinclude, but is not limited to, portable or fixed storage devices,optical storage devices, wireless channels and various other mediumscapable of storing, containing or carrying instruction(s) and/or data.

A code segment may represent a procedure, a function, a subprogram, aprogram, a routine, a subroutine, a module, a software package, a class,or any combination of instructions, data structures, or programstatements. A code segment may be coupled to another code segment or ahardware circuit by passing and/or receiving information, data,arguments, parameters, or memory contents. Information, arguments,parameters, data, etc. may be passed, forwarded, or transmitted via anysuitable means including memory sharing, message passing, token passing,network transmission, etc.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and/orthe present application, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

FIG. 1 is a block diagram of a system on chip (SoC) 10 according to anexample embodiment of inventive concepts.

Referring to FIG. 1, the SoC 10 includes a clock generator 110, a clockcontroller 100 and a function block 120. The SoC 10 may be manufacturedas a single chip in a single package. For clarity of the description,the SoC 10 including the clock generator 110, the clock controller 100and the function block 120 is illustrated in FIG. 1, but inventiveconcepts are not restricted thereto.

According to at least one example embodiment, the clock controller 100is configured to decrease an operating frequency of at least onefunction block based on a change in an operating state of the at leastone function block from an active state to an idle state, the decreasedoperating frequency being greater than zero.

According to at least one other example embodiment, the clock controller100 is configured to: detect a change in an operating state of afunction block 120 from an active state to an inactive state (e.g., idlestate); decrease an operating frequency of the function block 120 inresponse to the detected change, wherein the decreased operatingfrequency is greater than zero; detect a change in the operating stateof the function block 120 from the inactive state to the active state;and increase the operating frequency of the function block 120 inresponse to the detected change from the inactive state to the activestate.

In more detail with regard to FIG. 1, the clock generator 110 generatesa reference clock signal CLKin having a reference frequency for theoperation of the SoC 10. The clock generator 110 outputs the referenceclock signal CLKin to the clock controller 100.

The clock controller 100 monitors the state of the function block 120and sets an operating frequency of an operating clock signal CLKoutaccording to the monitored state of the function block 120. The clockcontroller 100 outputs the operating clock signal CLKout to the functionblock 120.

When the function block 120 is in the idle state, the clock controller100 outputs an operating clock signal CLKout having a first (idle mode)frequency (e.g., a given, desired or predetermined first frequency).When the function block 120 is in the active state, the clock controller100 outputs the operating clock signal CLKout having a second (activemode) frequency (e.g., a given, desired or predetermined secondfrequency) or third (wakeup mode) frequency (e.g., a given, desired orpredetermined third frequency). In one example, when the function block120 transitions from the idle state to the active state, the clockcontroller 100 outputs an operating clock signal CLKout having the thirdfrequency.

According to at least some example embodiments, the first through thirdfrequencies are greater than 0, and at least two of the threefrequencies are different from one another. According to at least someother example embodiments, the first through third frequencies aregreater than 0 and different from one another. The operating frequenciesmay gradually increase in order of the first frequency (sometimesreferred to herein as the “idle mode frequency” or “idle mode operatingfrequency”), the third frequency (sometimes referred to herein as the“wakeup mode frequency” or “wakeup mode operating frequency”), and thesecond frequency (sometimes referred to herein as the “active modefrequency” or “active mode operating frequency”). For example, thewakeup mode frequency is greater than the idle mode frequency, and theactive mode frequency is greater than the wakeup mode frequency. Again,each of the idle mode frequency, the wakeup mode frequency, and theactive mode frequency has a value greater 0, and the frequencies may bedifferent from one another.

Still referring to FIG. 1, the clock controller 100 includes a divider20 and a divider controller 30.

The divider controller 30 monitors the state of the function block 120,and outputs a division factor Div based on the monitored state of thefunction block 120. The divider 20 sets the operating frequency of theoperating clock signal CLKout to a frequency obtained by dividing thereference frequency by the division factor Div, and outputs theoperating clock signal CLKout having the obtained operating frequency.The divider controller 30 monitors the state of the function block 120based on the state signal State output from the function block 120.

In one example, when the state signal State output from the functionblock 120 is high (e.g., a logic high or ‘1’), the divider controller 30determines that the function block 120 is in the active state. On theother hand, when the state signal State output from the function block120 is low (e.g., a logic low or ‘0’), the divider controller 30determines that the function block 120 is in the idle state. Thefunction block 120 performs data processing operations in the SoC 10.Although only one function block 120 is illustrated in FIG. 1, inventiveconcepts are not restricted to only this example embodiment. The SoC 10may include a plurality of function blocks.

According to at least some example embodiments, the function block 120may be a processor controlling the entire SoC 10 or one of variousintellectual properties (IPs) controlled by the processor. Examples ofthe IPs include a central processing unit (CPU), cores of a CPU, agraphics processing unit (GPU), a multi-format codec (MFC), a videomodule (e.g., a camera interface, a Joint Photographic Experts Group(JPEG) processor, a video processor, a mixer, etc.), an audio system, adriver, a display driver, a volatile memory device, non-volatile memory,a memory controller, cache memory, a serial port, a system timer, awatchdog timer, an analog-to-digital converter, etc. Function blocks 120may have different operating clock frequencies and/or differentoperating clock frequency requirements, and therefore, differentoperating clock signals CLKout may be used in the SoC 10.

According to at least some example embodiments, the SoC 10 may beimplemented by an integrated circuit (IC). The SoC 10 may be embedded ina mobile communication device such as a mobile phone, a smart phone, atablet personal computer (PC), a personal digital assistant (PDA), a MP3player, a laptop computer, etc. The SoC 10 may also be embedded in aninformation technology (IT) device or other portable electronic device.

FIG. 2 is a more detailed block diagram of an example embodiment of theSoC 10 illustrated in FIG. 1.

Referring to FIG. 2, the divider controller 30 includes a register block32, a mode detector 35 and a selector 31. The register block 32 includesa plurality of registers Reg0 through Regn-1, where “n” is a naturalnumber greater than or equal to 3.

For clarity of the description, it is assumed that a frequency increasesin order of the first, third and second frequencies, and a divisionfactor decreases in order of first, third and second division factors.As discussed herein, the first division factor may be referred to as theidle mode division factor, the third division factor may be referred toas the wakeup mode division factor, and the second division factor maybe referred to as the active mode division factor. In this example, thewakeup mode frequency is greater than the idle mode frequency, and theactive mode frequency is greater than the wakeup mode frequency.Moreover, the wakeup mode division factor is less than the idle modedivision factor, and the active mode division factor is less than thewakeup mode division factor. However, inventive concepts are notrestricted to only the example embodiments discussed herein.

Still referring to FIG. 2, the register block 32 may store a pluralityof division factors D0 through Dn-1. When the register block 32 stores“n” division factors, each of the registers Reg0 through Regn-1 maystore a single division factor.

The mode detector 35 may be implemented in the form of a finite statemachine (FSM), which will be discussed in more detail later. In at leastone example embodiment, the mode detector 35 monitors the state of thefunction block 120 based on the state signal State. Based on themonitored state of the function block 120, the mode detector 35 entersone of a plurality of states (e.g., an idle mode, a wakeup mode and anactive mode), and outputs a select signal Se1 to the selector 31 basedon its mode. The selector 31 outputs a division factor Div from amongthe division factors D0 through Dn-1 in response to the select signalSel from the mode detector 35.

For example, when the mode detector 35 determines that the functionblock 120 is in the idle state, the mode detector 35 transitions to theidle mode (if not already in the idle mode) and outputs a first selectsignal Sel0. The selector 31 outputs the first (idle mode) divisionfactor D0 received from the register Reg0 in response to the firstselect signal Sel0.

The divider 20 then sets an operating frequency of the operating clocksignal CLKout to the idle mode frequency, which is obtained by dividingthe reference frequency by the idle mode division factor D0, and outputsthe operating clock signal CLKout having the idle mode frequency to thefunction block 120.

According to at least some example embodiments, if the function block120 transitions from the active state to the idle state, then thefrequency of the operating clock signal CLKout changes from the activemode frequency to the idle mode frequency in response to the change inthe state of the function block 120. As a result, unnecessaryconsumption of power may be reduced in the SoC 10.

When the function block 120 is in the active state, the mode detector 35transitions to the active mode (if not already in the active mode) andoutputs a second select signal Seln-1. The selector 31 outputs theactive mode division factor Dn-1 received from the register Regn-1 inresponse to the second select signal Seln-1.

The divider 20 then sets the operating frequency of the operating clocksignal CLKout to the active mode frequency obtained by dividing thereference frequency by the active mode division factor Dn-1, and outputsthe operating clock signal CLKout having the active mode frequency tothe function block 120.

When the function block 120 is in the idle state and then transitionsfrom the idle state to the active state, the state signal Statetransitions (e.g., from logic low to logic high). In response to thetransition of the function block 120 from the idle state to the activestate, the mode detector 35 transitions to the wakeup mode and outputsat least one third select signal Selk. The selector 31 outputs a wakeupmode division factor Dk from register Regk in response to the thirdselect signal Selk. In this example, k is one of 1, 2, . . . , n-2.Herein, n-2 is sometimes referred to as N. The divider 20 sets theoperating frequency of the operating clock CLKout to the wakeup modefrequency, which is obtained by dividing the reference frequency by thewakeup mode division factor Dk. The divider 20 then outputs theoperating clock signal CLKout having the wakeup mode frequency to thefunction block 120. The operating clock signal CLKout maintains thewakeup mode frequency until a given, desired or predetermined count timeafter the function block 120 transitions from the idle state to theactive state. That is, for example, the operating clock signal CLKoutmaintains the wakeup mode frequency until a given time period expires.In one example, the operating clock signal CLKout maintains the wakeupmode frequency until the mode detector 35 transitions from the wakeupmode to the active mode.

Still referring to FIG. 2, the mode detector 35 may include at least onecounter. The counter is configured to count the given, desired orpredetermined count time during which the operating frequency of theoperating clock CLKout is set to one of the at least one wakeup modefrequencies. While each count time for the respective at least onewakeup modes is being counted, the operating clock signal CLKout is setto one of the at least one wakeup mode frequencies. When the count timeelapses, the mode detector 35 transitions to the active mode and theoperating frequency is set to the active mode frequency.

If the operating frequency changes (e.g., abruptly changes) from theidle mode frequency to the active mode frequency when the function block120 transitions from the idle state to the active state, a suddenvoltage drop may cause the SoC 10 to malfunction. However, when thefunction block 120 operates with the wakeup mode frequency for a given,desired or predetermined count time (time period) after the functionblock 120 transitions from the idle state to the active state, thecurrent applied to the function block 120 gradually increases, andtherefore, the function block 120 operates normally without suddenvoltage drop.

FIG. 3 is a diagram illustrating an example embodiment of a finite statemachine (FSM) implementation of the mode detector 35 illustrated in FIG.2. In the example shown in FIG. 3, the mode detector 35 outputs theselect signal Sel to select the division factor Div according to themonitored state of the function block 120.

As is known, a FSM is a machine capable of having one of a finite numberof states. The machine is in only one state at a time, and the statethat the machine is in at any given time is called the current state.The FSM may change from one state to another when initiated by atriggering event or condition. The changing from one state to another isreferred to as a transition. A particular FSM is defined by a list ofthe possible transition states from each current state, and thetriggering condition for each transition. Because FSMs are generallywell-known, example embodiments of FSMs will be understood by those ofordinary skill in the art that various changes in forms and details maybe made therein without departing from the spirit and scope of inventiveconcepts.

Referring to FIG. 3, the FSM includes a plurality of (e.g., n) modes(e.g., limited modes) of the function block 120 as its states. The modesare linked to each other by certain conditions. The FSM may beimplemented in hardware, software or a combination thereof.

In one example, if the initial state of the function block 120 is theactive mode, then the mode detector 35 outputs an active mode selectsignal Seln-1 to select the active mode division factor Dn-1. Inresponse to the active mode select signal Seln-1, the selector 31selects the register Regn-1, and outputs the active mode division factorDn-1 to the divider 20.

When the state of the function block 120 transitions from the activestate to the idle state, the mode detector 35 detects that the functionblock 120 is in the idle state and transitions from the active mode tothe idle mode. In the idle mode, the mode detector 35, outputs an idlemode select signal Sel0 to select the idle mode division factor D0. Theselector 31 selects the register Reg0 in response to the idle modeselect signal Sel0 and outputs the idle mode division factor D0 to thedivider 20.

When the function block 120 transitions from the idle state to theactive state, the mode detector 35 detects the transition and enters thewakeup mode for a given, desired or predetermined period of time. Whilein the wakeup mode, the mode detector 35 outputs at least one wakeupmode select signal Selk. The selector 31 selects the register Regk inresponse to the wakeup mode select signal Selk, and outputs the wakeupmode division factor Dk to the divider 20. In this example, the at leastone wakeup mode select signal Selk is one of select signals Sel1 throughSeln-2. In this example, n is an integer indicative of the number ofdivision factors and modes of the FSM shown in FIG. 3, and n-2 isindicative of the number of stages in the wakeup mode.

Still referring to FIG. 3, the mode detector 35 may have one or morestages Wakeup1 through Wakeupn-2 in the wakeup mode. The wakeup modestages may be set in a given, desired or predetermined order, and theorder may be changed according to a users' setting or design processrequirements. The order may be transient from the idle mode frequency tothe active mode frequency. Count times Counter1 through Countern-2 areset for the respective wakeup mode stages Wakeup1 through Wakeupn-2.

The mode detector 35 allows each of the at least one wakeup modefrequencies to be applied as the operating frequency only for a given,desired or predetermined count time set for each wakeup mode frequency.When all of the count times expire, the mode detector 35 enters theactive mode and outputs the active mode select signal Seln-1.

FIG. 4 is a detailed block diagram of the SoC 10 illustrated in FIG. 1according to another example embodiment of inventive concepts. FIG. 5 isa diagram illustrating an example embodiment of a finite state machine(FSM) implementation of the mode detector 45 illustrated in FIG. 4.

In the example shown in FIGS. 4 and 5, it is assumed that there are atotal of three different division factors (n=3) by which the referencefrequency of the reference clock signal CLKin may be divided. The threedifferent division factors include: an idle mode division factor R0; awakeup mode division factor R1; and an active mode division factor R2.

When the initial state of the function block 120 is the active state,the mode detector 45 outputs an active mode select signal Sel2 to selectthe active mode division factor R2. In response to the active modeselect signal Sel2, a selector 41 selects a register Reg2, and outputsthe active mode division factor R2 to the divider 20.

When the mode detector 45 determines that the function block 120 is inthe idle state, the mode detector 45 outputs an idle mode select signalSel0 to select the idle mode division factor R0. In response to the idlemode select signal Sel0, the selector 41 selects a register Reg0, andoutputs the idle mode division factor R0 to the divider 20.

When the function block 120 transitions from the idle state to theactive state, the mode detector 45 transitions to the wakeup mode, andoutputs a wakeup mode select signal Sel1 to select the wakeup modedivision factor R1. The selector 41 selects a register Reg1 in responseto the wakeup mode select signal Sel1, and outputs the wakeup modedivision factor R1 to the divider 20. In one example, the idle modefrequency may be about half of the wakeup mode frequency.

FIG. 6 is a timing chart of signals of the SoC 10 according to anexample embodiment of inventive concepts.

Referring to FIG. 6, the operating frequency of the operating clocksignal CLKout when the function block 120 is in the active state isgreater than the operating frequency of the operating clock signalCLKout when the function block 120 is in the idle state.

Referring to FIGS. 4 and 6, the clock controller 100 monitors a statesignal State output from the function block 120. In one example, theclock controller 100 determines that the function block 120 is in theactive state when the state signal State is high, but determines thatthe function block 120 is in the idle state when the state signal Stateis low. However, example embodiments are not limited to this example.

According to at least one example embodiment, when the function block120 is in the active state, the clock controller 100 sets the operatingfrequency to the active mode frequency, and applies the operating clocksignal CLKout having the active mode frequency to the function block120. When the function block 120 transitions from the active state tothe idle state, the clock controller 100 sets the operating frequency tothe idle mode frequency and applies the operating clock signal CLKouthaving the idle mode frequency to the function block 120. When thefunction block 120 transitions from the idle state to the active state,the clock controller 100 sets the operating frequency to the active modefrequency and applies the operating clock signal CLKout having theactive mode frequency to the function block 120. Consequently,unnecessary consumption of power may be reduced because the functionblock 120 operates with the idle mode frequency, rather than the activemode frequency, in the idle state. In addition, when the operating clocksignal CLKout of the function block 120 cannot be gated, the idle modefrequency is continuously applied as the operating frequency, so thatthe function block 120 maintains functionality.

FIG. 7 is a timing chart of signals of the SoC 10 according to anotherexample embodiment of inventive concepts.

With regard to FIG. 7, the operations of the clock controller 100 aresimilar or substantially similar to those in the example embodimentillustrated in FIG. 6. For the sake of brevity, only differences betweenthe example embodiments illustrated in FIGS. 6 and 7 will be described.

Referring to FIG. 7, when the function block 120 transitions from theidle state to the active state, the clock controller 100 sets theoperating frequency of the function block 120 to a wakeup mode frequencyfor a given period, rather than to the active mode frequency as in FIG.6. As shown in FIG. 7, the wakeup mode frequency is greater than theoperating frequency of the operating clock signal CLKout during the idlestate, but less than the operating frequency of the operating clocksignal CLKout in the active state. That is, the wakeup mode frequency isgreater than the idle mode frequency, but less than the active modefrequency.

The operating clock signal CLKout having the wakeup mode frequency isapplied to the function block 120 for a given, desired or predeterminedcount time from the moment when the function block 120 transitions fromthe idle state to the active state. In one example, the wakeup modefrequency may be about half of the active mode frequency, but exampleembodiments are not restricted to this example. In at least some otherexample embodiments, the division factor Div corresponding to a mediumor intermediate frequency may be selected from among a group ofregisters to set the operating frequency.

When the operating clock signal CLKout with the active mode frequency isabruptly applied to the function block 120 in the idle state, a voltagedrop may occur due to the surge of current supplied to the functionblock 120. To suppress such a voltage drop, the wakeup mode frequency,which is between the idle mode frequency and the active mode frequency,is applied to the function block 120 for a given, desired orpredetermined count time (e.g., during the wakeup period or mode). As aresult, the function block 120 operates normally without a voltage dropcaused by the sudden change from the idle mode frequency to the activemode frequency, and malfunction of the function block 120 may besuppressed and/or prevented.

FIG. 8 is a timing chart of signals of the SoC 10 according to anotherexample embodiment of inventive concepts.

With regard to FIG. 8, the operations of the clock controller 100 aresimilar or substantially similar to those in the example embodimentillustrated in FIG. 7. For the sake of brevity, only differences betweenthe example embodiments illustrated in FIGS. 7 and 8 will be described.

In the example shown in FIG. 8, the wakeup mode of the mode detector 35includes a plurality of stages (e.g., at least two wakeup mode stages),rather than only a single wakeup mode state as in FIG. 7. For the sakeof this description, FIG. 8 shows that the wakeup mode has two stages,and that the wakeup mode frequency includes at least two wakeup modefrequencies (stages).

For a given, desired or predetermined first count time Wakeup1 after thefunction block 120 transitions from the idle state to the active state,the clock controller 100 sets the frequency of the operating clocksignal CLKout to a first wakeup mode frequency.

After expiration of the first count time Wakeup1, the clock controller100 sets the frequency of the operating clock signal CLKout to a secondwakeup mode frequency for a given, desired or predetermined second counttime Wakeup2. In this example, the first wakeup mode frequency and thesecond wakeup mode frequency are frequencies between the idle modefrequency and the active mode frequency, and the first wakeup modefrequency is less than the second wakeup mode frequency. At least twodifferent wakeup mode frequencies may be set by the mode detector forrespective count times.

With regard to at least some example embodiments, only two wakeup modestages and frequencies have been described. However, example embodimentsare not restricted to only these examples. In other example embodiments,more than two wakeup mode stages and frequencies may be implemented.

FIG. 9 is a block diagram of a SoC 10′ according to another exampleembodiment of inventive concepts. The SoC 10′ is similar to the SoC 10.Thus, for the sake of brevity, only differences between the exampleembodiments illustrated in FIGS. 2 and 9 will be explained in detail.

Referring to FIG. 9, the clock controller 100 includes a dividercontroller 50 and the divider 20. The divider controller 50 includes amode detector 55 and a look-up table (LUT) 53.

As with the mode detector 35, the mode detector 55 may also beimplemented in the form of a finite state machine (FSM). In at least oneexample embodiment, the mode detector 55 monitors the state of thefunction block 120. Based on the monitored state of the function block120, the mode detector 55 enters one of a plurality of states (e.g., anidle mode, at least one wakeup mode and an active mode). The modedetector 55 outputs a select signal D based on the entered state.

In this example, the operation of the mode detector 55 is the same orsubstantially the same as that of the mode detector 35 illustrated inFIG. 2. Thus, further discussion of the mode detector 55 is omitted.

Still referring to FIG. 9, the LUT 53 stores a plurality of divisionfactors. In example operation, the LUT 53 outputs one of the divisionfactors in response to the select signal D from the mode detector 55. Inmore detail, the LUT 53 may output an idle mode division factor when theselect signal D indicates the idle state, an active mode division factorwhen the select signal D indicates the active state, and at least onewakeup mode division factor when the select signal D indicates thewakeup state. In this example, the idle mode division factor, the activemode division factor and the at least one wakeup mode division factormay be different numbers, which are not 0. The idle mode division factormay be greater than the wakeup mode division factor, and the wakeup modedivision factor may be greater than the active mode division factor.

FIG. 10 is a flowchart illustrating a method of controlling a clocksignal according to an example embodiment of inventive concepts. For thesake of clarity, the method shown in FIG. 10 will be described withregard to the example embodiment shown in FIG. 2. However, the exampleembodiment shown in FIG. 10 is not limited to this implementation and/orexample.

Referring to FIG. 10, at operation S10 the mode detector 35 monitors thestate of the function block 120.

At operation Sll the mode detector 35 determines whether the functionblock 120 is in the idle state. If the function block 120 is in the idlestate, then the mode detector 35 determines whether the function block120 is at the moment or instant of transition from the idle state to theactive state at operation S12. If the function block 120 is not at themoment of transition (e.g., transition time) from the idle state to theactive state in operation S12, then the mode detector 35 enters the idlemode in operation S13 and outputs the selection signal Sel indicatingthe idle mode.

At operation S14, the clock controller 100 divides a frequency of thereference clock signal CLKin by the idle mode division factor. In thisexample, the idle mode division factor is a division factorcorresponding to the idle mode.

In operation S15, the clock controller 100 sets the operating frequencyof the function block 120 to the idle mode frequency obtained bydividing the reference clock frequency by the idle mode division factor.The clock controller 100 then provides an operating clock signal CLKouthaving the idle mode frequency to the function block 120 in operationS24. The process then returns to operation S10 in which the modedetector 35 monitors the state of the function block 120.

Returning to operation S12, if the mode detector 35 determines that thefunction block 120 is at the moment of transition from the idle state tothe active state, then the mode detector 35 transitions to the wakeupmode in operation S16 and outputs a selection signal Sel indicating thewakeup mode.

At operation S17, the clock controller 100 initializes a counter (e.g.,the counter discussed above with regard to FIG. 3). At operation S18,the clock controller 100 divides the frequency of the reference clocksignal CLKin by the wakeup mode division factor. In operation S19, theclock controller 100 sets the operating frequency to the wakeup modefrequency obtained by dividing the reference clock frequency by thewakeup mode division factor.

At operation S20 the clock controller 100 then checks whether a counttime of the initialized counter (operation S17) has elapsed. If thecount time has not elapsed, then the clock controller 100 provides theoperating clock signal having the wakeup mode frequency to the functionblock 120 in operation S24.

The clock controller 100 provides the operating clock signal CLKouthaving the wakeup mode frequency in operation S24 until a given, desiredor predetermined count time elapses in operation S20.

Returning to operation S20, if and when the count time has elapsed orexpired the mode detector 35 enters the active mode at operation S21.

The clock controller 100 then divides the frequency of the referenceclock signal by the active mode division factor in operation S22.

In operation S23, the clock controller 100 sets the operating frequencyto the active mode frequency obtained by dividing the frequency of thereference clock signal by the active mode division factor.

The clock controller 100 then provides the operating clock signal havingthe active mode frequency to the function block 120 in operation S24.

Returning to operation S11, if the function block 120 is not in the idlestate, then the process proceeds to operation S21 and continues asdiscussed above.

In at least the example embodiment shown in FIG. 10, the mode detector35 continuously monitors the state of the function block 120 even whenthe function block 120 operates according to an operating clock signalhaving a different frequency so that an operating clock signal isprovided to the function block 120 according to the current state of thefunction block 120 and/or transition of the state of the function block120.

FIG. 11 is a block diagram illustrating another example embodiment of aSoC.

Referring to FIG. 11, the SoC 10″ includes a clock controller 100′. Theclock controller 100′ includes a divider controller 30′ and a clocksignal multiplexer 1120. The divider controller 30′ includes a modedetector 35. The SoC 10″ further includes at least one function block120 and a plurality of clock generators 110 a, 110 b and 110 c. The modedetector 35 is the same or substantially the same as the mode detector35 shown in FIG. 2. Thus, a detailed discussion will be omitted for thesake of brevity.

As with the clock controller 100 shown in FIG. 2, the clock controller100′ monitors the state of the function block 120 and sets and operatingfrequency of the operating clock signal CLKout according to themonitored state of the function block 120. The clock controller 100′outputs the operating clock signal CLKout to the function block 120.

As mentioned above, the clock controller 100′ includes a dividercontroller 30′ and a clock signal multiplexer 1120.

The divider controller 30′ monitors the state of the function block 120,and outputs a select signal Sel based on the monitored state of thefunction block 120. The clock signal multiplexer 1120 selects one of aplurality of clock signals CLOCK A, CLOCK B and CLOCK C to output as theoperating clock signal CLKout based on the select signal Sel from themode detector 35.

The divider controller 30′ monitors the state of the function block 120based on the state signal State output from the function block 120.

In one example, when the state signal State output from the functionblock 120 is high (e.g., a logic high or ‘1’), the divider controller30′ determines that the function block 120 is in the active state. Onthe other hand, when the state signal output from the function block 120is low (e.g., a logic low or ‘0’), the divider controller 30′ determinesthat the function block 120 is in the idle state.

As mentioned above, the SoC 10″ shown in FIG. 11 includes a plurality ofclock signal generators 110 a through 110 c. Each of the clock signalgenerators 110 a through 110 c generates a respective one of theplurality of clock signals CLOCK A, CLOCK B and CLOCK C. In at leastthis example embodiment, each of the plurality of clock signals CLOCK A,CLOCK B and CLOCK C has a frequency corresponding to one of the idlemode frequency, the active mode frequency and the wakeup mode frequency.The idle mode frequency, the active mode frequency and the wakeup modefrequency are the same as those discussed above.

FIG. 12 is a block diagram illustrating yet another example embodimentof the SoC 10 shown in FIG. 1. The example shown in FIG. 12 is similarto the example shown in FIG. 2, but further includes a voltage detector31.

Referring to FIG. 12, the divider controller 30″ includes a registerblock 32, a mode detector 35′ and a selector 31. The register block 32and the selector 31 are the same or substantially the same as thoseshown in FIG. 2. Thus, a detailed description of these elements will beomitted for the sake of brevity.

The mode detector 35′ monitors the state of the function block 120 inthe same or substantially the same manner as the mode detector 35 inFIG. 2, and outputs a select signal Sel according to the monitored stateof the function block 120. The selector 31 outputs a division factor Divfrom among the division factors D0 through Dn-1 in response to theselect signal Sel.

For example, when the mode detector 35′ determines that the functionblock 120 is in the idle state, the mode detector 35′ outputs the idlemode select signal Sel0. The selector 31 outputs the idle mode divisionfactor D0 received from the register Reg0 in response to the idle modeselect signal Sel0 from the mode detector 35′.

The divider 20 then sets an operating frequency of the operating clocksignal CLKout to the idle mode frequency, which is obtained by dividingthe reference frequency by the idle mode division factor D0, and outputsthe operating clock signal CLKout having the idle mode frequency to thefunction block 120.

According to at least some example embodiments, when the function block120 transitions from the active state to the idle state, the frequencyof the operating clock signal CLKout changes from the active modefrequency to the idle mode frequency in response to the change in thestate of the function block 120. As a result, unnecessary consumption ofpower may be reduced in the SoC 10.

When the mode detector 35′ determines that the function block 120 is inthe active state, the mode detector 35′ outputs the active mode selectsignal Seln-1. The selector 31 outputs the active mode division factorDn-1 received from the register Regn-1 in response to the active modeselect signal Seln-1.

The divider 20 then sets the operating frequency of the operating clocksignal CLKout to the active mode frequency obtained by dividing thereference frequency by the active mode division factor Dn-1, and outputsthe operating clock signal CLKout having the active mode frequency.

When the function block 120 transitions from the idle state to theactive state, the mode detector 35′ enters the wakeup mode, and outputsat least one wakeup mode select signal Selk. The selector 31 outputs awakeup mode division factor Dk received from the register Regk inresponse to the wakeup mode select signal Selk. The divider 20 sets theoperating frequency of the operating clock CLKout to the wakeup modefrequency obtained by dividing the reference frequency by the wakeupmode division factor Dk. The divider 20 then outputs the operating clocksignal CLKout having the wakeup mode frequency.

Still referring to FIG. 12, the divider controller 30″ further includesa voltage level detector 1231. The voltage level detector 1231 monitorsthe voltage level of the function block 120, and outputs a voltage levelstability signal when the voltage level of the function block 120stabilizes after the operating frequency of the operating clock CLKoutis set to one of the at least one wakeup mode frequencies. In responseto the voltage level stability signal indicating that the voltage levelof the function block has stabilized, the mode detector 35′ transitionsto the active mode (or alternatively to the next wakeup mode stage) andoutputs the active mode select signal Sn-1 to set the operatingfrequency to the active mode frequency (or another of the wakeup modefrequencies).

FIG. 13 is a diagram illustrating an example embodiment of a finitestate machine (FSM) implementation of the mode detector 35′ illustratedin FIG. 12. In the example shown in FIG. 13, the mode detector 35′outputs the select signal Sel to select the division factor Divaccording to the current state of the function block 120.

As with the example embodiment shown in FIG. 3, the FSM shown in FIG. 13includes a plurality of (e.g., n-2) modes (e.g., limited modes) of thefunction block 120 as its states. The modes are linked to each other bycertain conditions. The FSM may be implemented in hardware, software ora combination thereof.

In one example, if the initial state of the function block 120 is theactive state, then the mode detector 35′ outputs the active mode selectsignal Seln-1 to select the active mode division factor Dn-1. Inresponse to the active mode select signal Seln-1, the selector 31selects the register Regn-1, and outputs the active mode division factorDn-1 to the divider 20.

When the state of the function block 120 transitions from the activestate to the idle state, the mode detector 35′ detects that the functionblock 120 is in the idle state, and outputs the idle mode select signalSel0 to select the idle mode division factor D0. The selector 31 selectsthe register Reg0 in response to the idle mode select signal Sel0 andoutputs the idle mode division factor D0 to the divider 20.

When the function block 120 transitions from the idle state to theactive state, the mode detector 35′ detects this transition and entersthe wakeup mode. While in the wakeup mode, the mode detector 35′ outputsat least one wakeup mode select signal Selk. The selector 31 selects theregister Regk in response to the wakeup mode select signal Selk, andoutputs the wakeup mode division factor Dk to the divider 20. In thisexample, the at least one wakeup mode select signal Selk is one ofwakeup mode select signals Sel1 through Seln-2, where n is an integerindicative of the number of division factors, and n-2 is indicative ofthe number of stages in the wakeup mode.

Still referring to FIG. 13, the wakeup mode may have one or more stagesWakeup1 through Wakeupn-2. The wakeup mode stages may be set in a given,desired or predetermined order. The order may be changed according to ausers' setting or design process requirements. The order may betransient from the idle mode frequency to the active mode frequency.

In this example embodiment, transitions between wakeup mode stages bythe mode detector 35′ are triggered by the voltage level detector 1231shown in FIG. 12. The mode detector 35′ applies the wakeup modefrequency (e.g., corresponding to a given stage of the wakeup mode) asthe operating frequency until the voltage level of the function block120 stabilizes. That is, for example, the mode detector 35′ allows thefrequency corresponding to each wakeup mode stage to be applied as theoperating frequency until the state of the SoC 10 changes (e.g.,stabilizes). When the voltage level of the function block 120 stabilizesafter the mode detector 35′ transitions to the final wakeup mode stage,the mode detector 35′ enters the active mode. The mode detector 35′ thenoutputs the active mode select signal Seln-1.

FIG. 14 is a block diagram illustrating another example embodiment ofthe SoC shown in FIG. 1. The example shown in FIG. 14 is similar to theexample shown in FIG. 2, but the clock controller 100 includes anoperating frequency setting circuit 60.

Referring to FIG. 14, the clock controller 100 includes a mode detectorcircuit 35 and an operating frequency setting circuit 60. The modedetector circuit 35 detects a change in an operating state of a functionblock 120 and generates a select signal based on the detected change inthe operating state. The operating frequency setting circuit 60 sets anoperating frequency of the function block based on the select signalfrom the mode detector circuit.

The operating frequency setting circuit 60 decreases the operatingfrequency of the function block 120 if the select signal Sel isindicative of a change from an active operating state to an inactiveoperating state, the decreased operating frequency being greater thanzero. The operating frequency setting circuit 60 increases the operatingfrequency of the function block 120 if the select signal Sel isindicative of a change from the inactive operating state to the activeoperating state.

In other example, if the select signal Sel is indicative of the changefrom the inactive operating state to the active operating state, theoperating frequency setting circuit 60 increases the operating frequencyof the function block 120 from a first frequency to a second frequency,and increases the operating frequency from the second frequency to athird frequency after expiration of a first time period after the changein the operating state of the function block 120 from the inactiveoperating state to the active operating state. The operating frequencysetting circuit 60 increases the operating frequency from the thirdfrequency to a fourth frequency after expiration of a second time periodafter the change in the operating state of the function block 120 fromthe inactive operating state to the active operating state.

The operating frequency setting circuit 60 comprises a divider circuit63, a selection circuit 61 and a register block 62. The divider circuit63, the selection circuit 61 and the register block 62 are the same orsubstantially the same as those shown in FIG. 2. Thus, a detaileddescription of these elements will be omitted for the sake of brevity.

FIG. 15 is a block diagram illustrating yet another example embodimentof the SoC shown in FIG. 1. The example shown in FIG. 15 is similar tothe example shown in FIG. 14, but the operating frequency settingcircuit 60 includes a look-up table 71.

Referring to FIG. 15, the look-up table 71 stores a plurality ofdivision factors and outputs a selected one of the plurality of divisionfactors Div in response to the select signal D from a mode detectorcircuit 55. The mode detector circuit 55 and the divider circuit 72 arethe same or substantially the same as those shown in FIG. 2. Thus, adetailed description of these elements will be omitted for the sake ofbrevity.

FIG. 16 is a block diagram of a semiconductor system 1000 including aSoC 200 according to an example embodiment of inventive concepts.

Referring to FIG. 16, the semiconductor system 1000 may be implementedas a handheld device such as a cellular telephone, a smart phone, atablet computer, a personal digital assistant (PDA), an enterprisedigital assistant (EDA), a digital still camera, a digital video camera,a portable multimedia player (PMP), a personal navigation device orportable navigation device (PND), a handheld game console, an e-book, orthe like.

The semiconductor system 1000 includes the SoC 200, an oscillator 210,an external memory 220 and a display device 230. The SoC 200 may be anapplication processor and corresponds to a SoC according to an exampleembodiment as described herein. The application processor may controlthe overall operation of the semiconductor system 1000.

The SoC 200 may include the clock controller 100, the clock generator110, a central processing unit (CPU) 120, a graphics processing unit(GPU) 125, a liquid crystal display (LCD) controller 130, read onlymemory (ROM) 140, random access memory (RAM) 160, a memory controller150 and a bus. The SoC 200 may also include other elements, such as apower management unit, a television (TV) processor, etc. A functionblock may refer to the CPU 120, the GPU 125, the memory controller 150or a peripheral circuit control unit (not shown).

The CPU 120 may process or execute programs and/or data stored in thememory 150 or 220. For instance, the CPU 120 may process or execute theprograms and/or the data in response to an operating clock signal outputfrom the clock controller 100.

The CPU 120 may be implemented by a multi-core processor. A multi-coreprocessor is a single computing component with two or more independentactual processors (referred to as cores). Each of the processors mayread and execute program instructions. The multi-core processor maydrive a plurality of accelerators at a time, and therefore, a dataprocessing system including the multi-core processor may performmulti-acceleration.

The GPU 125 may reduce the load of the CPU 120 by reading and executingprogram instructions related to graphics processing. The GPU 125receives data from the memory 220 through a memory interface (not shown)and transmits processed data to the memory 220 through the memoryinterface. The GPU 125 may process or execute the programs and/or thedata in response to the operating clock signal output from the clockcontroller 100.

The programs and/or the data stored in the memory 220 may be loaded tothe CPU 120 or the GPU 125 when necessary.

The ROM 140 may store permanent programs and/or data. The ROM 140 may beimplemented as erasable programmable ROM (EPROM) or electricallyerasable programmable ROM (EEPROM).

The RAM 160 may temporarily store programs, data and/or instructions.The programs and/or data stored in the memory 220 may be temporarilystored in the RAM 160 according to the control of the CPU 120 or abooting code stored in the ROM 140. The RAM 160 may be implemented bydynamic RAM (DRAM) and/or static RAM (SRAM).

The memory controller 150 interfaces with the external memory 220. Thememory controller 150 controls the overall operation of the externalmemory 220 and controls the data communication between a host and theexternal memory 220. The memory controller 150 may control the externalmemory 220 to write or read data at the request of the host. The hostmay be a master device such as the CPU 120 or the LCD controller 130.

The external memory 220 is a storage for storing data and may store anoperating system (OS) as well as various kinds of programs and data. Theexternal memory 220 may be implemented by DRAM, but inventive conceptsare not restricted to these example embodiments. The external memory 220may be implemented by non-volatile memory such as flash memory,phase-change RAM (PRAM), magnetoresistive RAM (MRAM), resistive RAM(ReRAM), ferroelectric RAM (FeRAM), etc. In other example embodiments,the external memory 220 may be embedded in the SoC 200.

The elements of the SoC 200 may communicate with one another through thebus.

The display device 230 may display multimedia loaded to the functionblock 120. According to at least this example embodiment, the displaydevice 230 is an LCD device. However, inventive concepts are notrestricted to this example embodiment. In at least some other exampleembodiments, the display device 230 may be a light emitting diode (LED)display device, an organic LED (OLED) display or one of other types ofdisplay devices.

The display device controller 130 controls the operations of the displaydevice 230.

FIG. 17 is a block diagram of a semiconductor system 400 including theSoC 10 illustrated in FIG. 1 according to an example embodiment ofinventive concepts. Although the semiconductor system 400 is shown inFIG. 17 as including the SoC 10, the semiconductor system 400 mayinclude one or more SoCs according to any of the example embodimentsdescribed herein.

Referring to FIG. 17, the semiconductor system 400 includes the SoC 10illustrated in FIG. 1, an antenna 401, a radio transceiver 403, an inputdevice 405 and a display 407.

The radio transceiver 403 transmits and receives radio signals throughthe antenna 401. The radio transceiver 403 may convert radio signalsreceived through the antenna 401 into signals that can be processed bythe SoC 10. Accordingly, the SoC 10 may process the signals output fromthe radio transceiver 403 and transmit the processed signals to thedisplay 407. And, the radio transceiver 403 may also convert signalsoutput from the SoC 10 into radio signals and output the radio signalsto an external device through the antenna 401.

The input device 405 enables control signals for controlling theoperation of the SoC 10 or data to be processed by the SoC 10 to beinput to the semiconductor system 400. The input device 405 may beimplemented by a pointing device such as a touch pad or a computermouse, a keypad, or a keyboard.

FIG. 18 is a block diagram of a computer system 500 including the SoC 10illustrated in FIG. 1 according to another example embodiment ofinventive concepts. The computer system 500 may be implemented as apersonal computer (PC), a tablet PC, a netbook, an e-reader, a PDA, aportable multimedia player (PMP), an MP3 player, an MP4 player, etc.Although the computer system 500 is shown in FIG. 16 as including theSoC 10, the computer system 500 may include one or more SoCs accordingto any of the example embodiments described herein.

The computer system 500 includes the SoC 10, a memory device 501, amemory controller 502 controlling the data processing operations of thememory device 501, a display 503 and an input device 504.

The SoC 10 may display data stored in the memory device 501 through adisplay 503 according to data input through an input device 504. Theinput device 504 may be implemented by a pointing device such as a touchpad or a computer mouse, a keypad, or a keyboard.

The SoC 10 may also control the overall operation of the computer system500 and the operations of the memory controller 502. The memorycontroller 502, which may control the operations of the memory device501, may be implemented as a part of the SoC 10 or as a separate chip.

FIG. 19 is a block diagram of a computer system 600 including the SoC 10illustrated in FIG. 1 according to another example embodiment ofinventive concepts. The computer system 600 may be implemented as animage processor of a digital camera, a cellular phone equipped with adigital camera, a smart phone equipped with a digital camera, a tabletPC equipped with a digital camera, or the like. Although the computersystem 600 is shown in FIG. 19 as including the SoC 10, the computersystem 600 may include one or more SoCs according to any of the exampleembodiments described herein.

The computer system 600 includes the SoC 10, a memory device 601 and amemory controller 602 controlling the data processing operations, suchas a program operation, an erase operation, and a read operation, of thememory device 601. The computer system 600 further includes an imagesensor 603 and a display 604.

The image sensor 603 included in the computer system 600 convertsoptical images into digital signals and outputs the digital signals tothe SoC 10 or the memory controller 602. The digital signals may becontrolled by the SoC 10 to be displayed through the display 604 orstored in the memory device 601 through the memory controller 602.

Data stored in the memory device 601 may be displayed through thedisplay 604 according to the control of the SoC 10 or the memorycontroller 602. The memory controller 602, which may control theoperations of the memory device 601, may be implemented as a part of theSoC 10 or as a separate chip.

FIG. 20 is a block diagram of a memory system 700 including the SoC 10illustrated in FIG. 1 according to still another example embodiment ofinventive concepts. The memory system 700 may be implemented as a datastorage system, such as a solid state drive (SSD). Although the memorysystem 700 shown in FIG. 20 includes the SoC 10, the memory system 700may include one or more SoCs according to any of the example embodimentsdescribed herein.

The memory system 700 includes a plurality of memory devices 701, amemory controller 702 controlling the data processing operations of thememory devices 701, a volatile memory device 703, such as a dynamicrandom access memory (DRAM), and the SoC 10 controlling data transferredbetween the memory controller 702 and a host 704 to be stored in thevolatile memory device 703.

As mentioned above, example embodiments of inventive concepts may alsobe embodied as computer-readable codes stored on a computer-readablemedium. The computer-readable recording medium may be any data storagedevice capable of storing data as a program, which can be thereafterread by a computer system. Examples of the computer-readable recordingmedium include read-only memory (ROM), random-access memory (RAM),CD-ROMs, magnetic tapes, floppy disks, and optical data storage devices.The computer-readable medium may also be distributed over networkcoupled computer systems so that the computer-readable code is storedand executed in a distributed fashion. Also, functional programs, codes,and code segments to accomplish the present inventive concepts can beeasily construed by programmers.

FIG. 21 is a graph showing current and voltage when an operating clocksignal is applied to the function block 120 without considering ortaking into account the state of the function block 120. FIG. 22 is agraph showing current and voltage when an operating clock signal isapplied to the function block 120 when considering (taking into account)the state of the function block 120.

Referring to FIG. 21, when the operating clock signal is applied to thefunction block 120 without considering the state of the function block120, voltage drop A occurs. However, as shown in FIG. 22, when theoperating clock signal with the third frequency is applied to thefunction block 120 at the transition of the function block 120 from anidle state to an active state, a voltage V is applied gradually to thefunction block 120, and therefore, voltage drop B is decreased ascompared to the voltage drop A.

When the operating clock signal is applied to the function block 120without considering the state of the function block 120, the operatingclock signal with the active state frequency, which is much greater thanthe idle state frequency, is abruptly applied to the function block 120and the slope of current I increases (e.g., rapidly increases) as shownin FIG. 21. However, when the operating clock signal with the wakeupstate frequency is applied to the function block 120 after the functionblock 120 transitions from the idle state to the active state, thecurrent I is gradually supplied to the function block 120, andtherefore, the slope of the current I increases relatively modestly orslowly as shown in FIG. 22. As a result, the function block 120 operatesnormally without malfunction caused by the relatively large voltage dropA and/or the relatively rapid increase in the slope of the current I.

In at least some example embodiments of methods of controlling clocksignals of SoCs, SoCs using the methods and semiconductor systemsincluding the SoCs, an operating clock signal applied to each of aplurality of function blocks is separately controlled according to thestate of each function block, so that unnecessary consumption of poweris reduced. In addition, malfunctions that may occur when the functionblock transitions from an idle state to an active state is suppressedand/or prevented.

While inventive concepts have been particularly shown and described withreference to example embodiments thereof, it will be understood by thoseof ordinary skill in the art that various changes in forms and detailsmay be made therein without departing from the spirit and scope ofinventive concepts as defined by the following claims.

1. A method of operating a system-on-chip including at least onefunction block, the method comprising: decreasing an operating frequencyof the at least one function block based on a change in an operatingstate of the at least one function block from an active state to an idlestate, the decreased operating frequency being greater than zero.
 2. Themethod of claim 1, wherein the decreasing of the operating frequencycomprises: dividing a frequency of a reference clock for thesystem-on-chip according to a division factor associated with the idlestate of the at least one function block; and wherein the operatingfrequency of the at least one function block is decreased to the dividedfrequency.
 3. The method of claim 1, further comprising: setting theoperating frequency of the at least one function block to an active modeoperating frequency, the active mode operating frequency being a firstclock frequency associated with the active state of the at least onefunction block; and wherein the operating frequency of the at least onefunction block is decreased from the active mode operating frequency toan idle mode operating frequency, the idle mode operating frequencybeing a second clock frequency associated with the idle state of the atleast one function block.
 4. The method of claim 1, further comprising:increasing the operating frequency of the at least one function block inresponse to a change in the operating state of the at least one functionblock from the idle state to the active state.
 5. (canceled)
 6. Themethod of claim 1, wherein the decreasing of the operating frequencycomprises: selecting a division factor from among a plurality ofdivision factors, the selected division factor corresponding to the idlestate; and setting the operating frequency of the at least one functionblock based on the selected division factor. 7.-14. (canceled)
 15. Themethod of claim 1, wherein the decreasing of the operating frequencycomprises: selecting an operating clock from among a plurality ofoperating clocks based on the operating state of the at least onefunction block, the selected operating clock corresponding to the idlestate. 16.-24. (canceled)
 25. A method of operating a system-on-chipincluding a function block, the method comprising: detecting a firstchange in an operating state of the function block from an active stateto an inactive state; decreasing an operating frequency of the functionblock in response to the detected first change, the decreased operatingfrequency being greater than zero; detecting a second change in theoperating state of the function block from the inactive state to theactive state; and increasing the operating frequency of the functionblock in response to the detected second change from the inactive stateto the active state. 26.-35. (canceled)
 36. A system-on-chip comprising:a clock controller configured to decrease an operating frequency of atleast one function block based on a change in an operating state of theat least one function block from an active state to an idle state, thedecreased operating frequency being greater than zero.
 37. Thesystem-on-chip of claim 36, wherein the clock controller comprises: adivider circuit configured to divide a frequency of a reference clockfor the system-on-chip according to a division factor associated withthe idle state of the at least one function block to set the operatingfrequency of the at least one function block.
 38. The system-on-chip ofclaim 36, wherein the clock controller is further configured to set theoperating frequency of the at least one function block to an active modeoperating frequency, the active mode operating frequency being a firstclock frequency associated with the active state of the at least onefunction block, and wherein the clock controller is configured todecrease the operating frequency of the at least one function block fromthe active mode operating frequency to an idle mode operating frequency,the idle mode operating frequency being a second clock frequencyassociated with the idle state of the at least one function block. 39.The system-on-chip of claim 36, wherein the clock controller is furtherconfigured to increase the operating frequency of the at least onefunction block in response to a change in the operating state of the atleast one function block from the idle state to the active state. 40.The system-on-chip of claim 39, wherein the operating frequency isincreased to a wakeup mode operating frequency, the wakeup modeoperating frequency being an operating frequency associated with theactive state, and wherein the clock controller is further configured toincrease the operating frequency of the at least one function block fromthe wakeup mode operating frequency to an active mode operatingfrequency in response to expiration of a first time period after theoperating state of the at least one function block changes from the idlestate to the active state.
 41. The system-on-chip of claim 36, whereinthe clock controller comprises: a mode detector configured to detect theoperating state of the at least one function block; and a selectioncircuit configured to select one of a plurality of division factorsbased on the detected operating state of the at least one functionblock; wherein the clock controller is further configured to set theoperating frequency of the function block based on the selected divisionfactor.
 42. The system-on-chip of claim 41, wherein the clock controllerfurther comprises: a divider circuit configured to divide a frequency ofa reference clock based on the selected division factor to set theoperating frequency of the at least one function block.
 43. Thesystem-on-chip of claim 41, wherein the mode detector is furtherconfigured to generate a selection signal based on the detectedoperating state of the at least one function block, and wherein theselection circuit is further configured to select the one of theplurality of division factors based on the select signal.
 44. Thesystem-on-chip of claim 41, further comprising: a register blockconfigured to store the plurality of division factors, wherein theselection circuit is configured to select the one of the plurality ofdivision factors from the register block.
 45. The system-on-chip ofclaim 44, wherein the clock controller comprises: a divider circuitconfigured to divide a frequency of a reference clock based on theselected division factor to set the operating frequency of the functionblock.
 46. The system-on-chip of claim 44, wherein the mode detector isfurther configured to generate a select signal based on the detectedoperating state of the function block, and wherein the selection circuitis further configured to select one of the plurality of division factorsfrom the register block based on the select signal.
 47. Thesystem-on-chip of claim 36, further comprising: a mode detectorconfigured to detect the operating state of the at least one functionblock; and a look-up table configured to store a plurality of divisionfactors, the look-up table being further configured to output one of theplurality of division factors based on the detected operating state,wherein the clock controller is further configured to set the operatingfrequency of the at least one function block based on the outputdivision factor.
 48. The system-on-chip of claim 47, wherein the clockcontroller comprises: a divider circuit configured to divide a frequencyof a reference clock based on the output division factor to set theoperating frequency of the at least one function block.
 49. Thesystem-on-chip of claim 47, wherein the mode detector is furtherconfigured to generate a select signal based on the detected operatingstate of the function block, and wherein the look-up table is furtherconfigured to output the one of the plurality of division factors basedon the select signal.
 50. The system-on-chip of claim 36, furthercomprising: a selection circuit configured to select one of a pluralityof operating clocks based on the operating state of the at least onefunction block; wherein the clock controller is further configured toset the operating frequency to a frequency of the selected operatingclock.
 51. The system-on-chip of claim 50, further comprising: aplurality of phase-locked-loop (PLL) circuits configured to generate theplurality of operating clocks, each of the plurality of operating clockshaving an operating frequency from among a plurality of operatingfrequencies.
 52. The system-on-chip of claim 36, wherein the clockcontroller comprises: a mode detector circuit configured to detect achange in the operating state of the function block from the idle stateto the active state; and wherein the clock controller is furtherconfigured to increase the operating frequency of the function block inresponse to the detected change from the idle state to the active state.53. The system-on-chip of claim 52, wherein the clock controller isconfigured to increase the operating frequency gradually.
 54. Thesystem-on-chip of claim 52, wherein the clock controller is furtherconfigured to increase the operating frequency of the at least onefunction block from a first frequency to a second frequency, to detect achange in state of the system-on-chip, and to increase the operatingfrequency from the second frequency to a third frequency in response tothe detected change in state of the system-on-chip.
 55. Thesystem-on-chip of claim 54, wherein the increase in the operatingfrequency from the second frequency to the third frequency is triggeredby a voltage detector.
 56. The system on chip of claim 54, wherein theclock controller is further configured to increase the operatingfrequency from the third frequency to a fourth frequency in response todetection of a change in state of the system-on-chip.
 57. Thesystem-on-chip of claim 52, wherein the clock controller is furtherconfigured to increase the operating frequency from a first frequency toa second frequency, and to increase the operating frequency from thesecond frequency to a third frequency after expiration of a first timeperiod after the operating state changes from the idle state to theactive state.
 58. The system-on-chip of claim 57, wherein the clockcontroller is further configured to increase the operating frequencyfrom the third frequency to a fourth frequency after expiration of asecond time period after increasing the operating frequency form thesecond frequency to the third frequency, and wherein the fourthfrequency is a frequency corresponding to the active state of thefunction block.
 59. A system-on-chip comprising: a mode detector circuitconfigured to detect a change in an operating state of a function block,the mode detector circuit being further configured to generate a selectsignal based on the detected change in the operating state; and anoperating frequency setting circuit configured to set an operatingfrequency of the function block based on the select signal from the modedetector circuit; wherein the operating frequency setting circuit isconfigured to decrease the operating frequency of the function block ifthe select signal is indicative of a change from an active operatingstate to an inactive operating state, the decreased operating frequencybeing greater than zero, and the operating frequency setting circuit isconfigured to increase the operating frequency of the function block ifthe select signal is indicative of a change from the inactive operatingstate to the active operating state.
 60. The system-on-chip of claim 59,wherein, if the select signal is indicative of the change from theinactive operating state to the active operating state, the operatingfrequency setting circuit is configured to increase the operatingfrequency of the function block from a first frequency to a secondfrequency, and to increase the operating frequency from the secondfrequency to a third frequency after expiration of a first time periodafter the change in the operating state of the function block from theinactive operating state to the active operating state.
 61. Thesystem-on-chip of claim 60, wherein the operating frequency settingcircuit is further configured to increase the operating frequency fromthe third frequency to a fourth frequency after expiration of a secondtime period after the change in the operating state of the functionblock from the inactive operating state to the active operating state.62. The system-on-chip of claim 59, wherein the operating frequencysetting circuit comprises: a divider circuit configured to divide afrequency of a reference clock for the system-on-chip according to adivision factor associated with the operating state of the functionblock to set the operating frequency of the function block.
 63. Thesystem-on-chip of claim 59, wherein the operating frequency settingcircuit comprises: a selection circuit configured to select one of aplurality of division factors based on the select signal; and whereinthe operating frequency setting circuit is configured to set theoperating frequency of the function block based on the selected divisionfactor.
 64. The system-on-chip of claim 63, wherein the operatingfrequency setting circuit comprises: a divider circuit configured todivide a frequency of a reference clock based on the selected divisionfactor to set the operating frequency of the function block.
 65. Thesystem-on-chip of claim 63, wherein the operating frequency settingcircuit further comprises: a register block configured to store theplurality of division factors, wherein the selection circuit isconfigured to select the one of a plurality of division factors from theregister block.
 66. The system-on-chip of claim 65, wherein theoperating frequency setting circuit further comprises: a divider circuitconfigured to divide a frequency of a reference clock based on theselected division factor to set the operating frequency of the functionblock.
 67. The system-on-chip of claim 59, further comprising: a look-uptable configured to store a plurality of division factors, the look-uptable being further configured to output a selected one of the pluralityof division factors in response to the select signal, wherein theoperating frequency setting circuit is configured to set the operatingfrequency of the function block based on the selected division factor.68. The system-on-chip of claim 67, wherein the operating frequencysetting circuit further comprises: a divider circuit configured todivide a frequency of a reference clock based on the selected divisionfactor to set the operating frequency of the function block. 69.-73.(canceled)